Improvement in bleaching paper-pulp



' @UNIJTE STATES PATENT OFFICE. v

Jos. e. KENDALL, OF WORCESTER, AND J. H. KENDALL, .OF LEOMINSTER,

MASSACHUSETTS.

- IMPROVEMENT INBLEACHING PAPER-PULP.

Specification forming part of Letters Patent No. 4,6I6, dated July 2,1846; antedated January2,,1846.'

To all whom it may conccrn:

Be it known that we, JOSEPH G.,KEND ALL, of Worcestenand J ONAS H.KENDALL, of Leominster, both in the county-of Worcester and Commonwealthof Massachusetts, have in vented, jointly, a new and useful process ormethod of nsin gand applying the bleaching substances hereinafter namedin the bleaching of rags, cotton waste, bagging, and other materials ofvwhich paper ismade after the same have been washed or reduced tohalf-pulp in the washing-engines and are discharged intothe commonchests or drainers, which are nearly filled with such washed stockorrags, &c., the, gine of washed stock is' discharged into the chest ordrainer, and it is as full of, washed water being first drained fromsuch stock in said chests or drainers; and we do hereby declare that thefollowing is a full and exact description of such process or method.

The improvement for which a patent is sought consists in theapplicationof well-known bleaching substances to the material used in makingpaper-as cotton, linen, hemp, &c .after the same has been washed in theengines of a paper-mill and is discharged into chests or drainers; or,in other words, the improvement con-- sists in the process or mode ofapplication of such-bleaching substances in such chests or drainers.

Before describing this process it may be well to premise that an engineis a vat holding water,wherein revolves a heavy roll having thereonfixed bars of iron and steel, whereby the rags, &c., are washed andreduced to halfpulp and afterward beat or reduced to pulp. Thismachinery is the engine. The chests or drainers are large wooden vats orcisterns holding from one to ten or more tons of washed stock or rags,&c., reduced tohalf-pulp. I It may be further premised that in usingthis improvementitis understood that when the wash ing process is nearlycompleted the washed stock or rags, &c., is bleached in the engines,and, if it be colored stock, that it has been boiled in lime or alkalibefore the washing in the engine. The said bleaching in the engine isthe using of three or four pounds of chloride of lime dissolved and putinto the engine at the close of the washing process, and the usualquantity of alum or acid is also added to the stock in the engine, andafter a suitable time the whole is discharged into achest ordrain'er;

and from that the water in a few hours runs out and the washed stock orrags remains in charged into a chest or drainer till it isfivesixthsorseven-eighths filledwith washedstock; "The chests ordrainers are either not made water-tight or, if so, are so made thatthexwater can be run or drained off and leave thechest ffilled, asaforesaid,with the washed stock in 'awet state; In twelve hours afterthe lastenstock as aforesaid, or as is desired, the waterwill be sodrained off that the process-herein. claimed as an improvement may becommenced. 4 The upper surface of the washed stock in thechest must bemade level. It will not be so at. this stage, for as the water drainsoff and the stock closes an interval is made between thesides of thechest or drainer and the washed stock. This interval must be filled upby tak- 5 in g the stock from the highest or central parts of the sameand putting it into this interval and pressing it down therein, and somaking.

the top or upper surface of the bleached stock level and nearlyhorizontal. By this leveling and pressing down the stock the bleachingand the water containingit, hereinafter described, will, when firstdischarged on the top of the washed stock so leveled, cover the top ofthe washed-stock of an equal depth, and so,when it.

passes down through the same, every part of; the same will have an equalportionof bleaching and the-mass be uniformly bleached. Then fill theengine (one by which the washed stock has beenprepared), with clearwhite water, and. into'the water pour and'well mix with it'forty poundsof sulphuric acid for each ton of washed stock to be bleached in thechest or drainer. Here and elsewhere in this specification,when a ton ortons of washed stock or rags, &c., are mentioned, a ton or tons of drystockisintended, and not a ton or tons of wet stock, so that a ton ofwashed stock means a quantity which, if dried, would weigh a ton. Theabove forty pounds of acid per ton of washed stock is suf-

